Isolated water voles in London are being provided with miniature ladders to encourage them to venture further afield.
The wooden “superhighways” will allow voles to cross over high, vertical edges along the Grand Union Canal to reach new territories.
Conservationists hope the ladders could eventually be used nationwide to help genetically-isolated water voles on the UK’s canals to meet and mix with other populations.
The ladders are being installed as part of a conservation project by the Canal and River Trust, which aims to reverse the dramatic decline in the UK’s water voles in recent years.
They are being used for a small colony of water voles living at Hanwell Lock Flight, Ealing. But if successful, the ladders could be rolled out nationally as a new way of helping voles travel across canal banks.
The structures will allow the vole colony access to newly-constructed floating islands on the Grand Union Canal.
The manmade islands have been planted with vegetation for voles to nest in and feed on with the intention of extending the mammals’ habitat and encouraging them to utilise more of the waterway.
Until now the voles have lived solely on a pond adjacent to the canal.
Similar constructions have been used in the past, most notably a ladder to help otters take a short cut over a dam at Ladybower reservoir, Derbyshire, instead of having to cross a road to reach the water body.
But the conservation team believe this project is the first time ladders have been used for the UK’s water voles.
“I’m quite confident that [the voles] will use these ramps,” said Canal and River Trust ecologist Leela O’Dea.
Before the installation of the ramps, tall steel sheets used along the canal edge had prevented voles living in the bank-side pond from using the canal.
“The water voles will be able to move from the pond, onto the floating islands, and then back up to the pond again. So we’re basically just extending the habitat we have available,” said Ms O’Dea.
She added that the conservation team would prefer to make canal banks “soft” so voles can burrow into them, but that the ladders provide a novel solution when this is not possible, such as when contaminated land restricts how canal banks can be altered.
The UK water vole population has declined by over 90% since the 1970s, largely due to habitat loss and predation by mink, according to the Canal and River Trust.
Slow-moving canals can act as ideal habitats for water voles, but many populations living in and around the waterways remain in one area and become genetically isolated.
“A lot of our water voles are in very small population groups which are fragmented, and that’s a common thing you get as animals become more endangered,” explained Ms O’Dea.
“But that does mean that they’re not mixing with the next population that could be some 2km away.
“So it is really important to try to look at linear and lateral corridors to get the voles moving amongst themselves because we’ll improve the genetic diversity and also improve their breeding habitat… improving their chance of surviving.”
Ms O’Dea commented that while the exact consequences of a lack of genetic diversity in voles is unclear, if populations become “too inbred”, they might be “more prone to different diseases” as well as “various genetic abnormalities that are going to be fed into all the [later] generations”.
The Canal and River Trust’s £100,000 conservation scheme will oversee projects in a number of England’s canals, including adapting canal banks so they provide new homes for voles to burrow, and joining up more pockets of prime habitat to help the species spread.